The United States has admitted that its plans of training Syrian fighters to battle the onslaught of the Islamic State has fallen behind schedule, with only 60 fighters currently under training. The announcement on Tuesday implies that the screening of recruits has severely thinned out the trainees' numbers.

The program, which was launched in May, is aimed at training 5,400 fighters a year. It was one of the key programs launched under the command of U.S. President Barack Obama, who has so far preferred to have U.S. military forces operate away from the front lines, according to Reuters.

The program also aims to train fighters that will specifically target the Islamic State.

Republican Senator John McCain, who is serving as the chairman of the Senate Armed Services Committee, believes that the poor numbers indicate that achieving the program's initial goal is doubtful.

"Given the poor numbers of recruited and trained Syrian fighters thus far, I am doubtful we can achieve our goal of training a few thousand this year," he said.

The number of significant challenges has weighed down the training program from the start however, as the U.S. military training focuses only on targeting ISIL. A huge portion of the trainees were aiming for battle against Syrian government forces, who are currently off-limits to U.S. offensive operations, reports Al Jazeera.

Defense Secretary Ash Carter remains optimistic about the program, however, stating that the numbers would improve as soon as the U.S. forces learned how to streamline its vetting processes.

"We will do more to train and equip the moderate opposition in Syria," he said. "We are also refining our curriculum, expanding our outreach to the moderate opposition, and incorporating lessons learned from the first training class."